Journeyman Plumbers General Plumbing Regulations Questions and Answers — Questions and Answers
Question 1: Under which of the following circumstances is a combination waste and vent system typically permitted by most plumbing codes?
- For floor drains and sinks in specific applications like laboratories where conventional venting is structurally impractical. (Correct answer)
- As a primary venting method for multi-story residential buildings to save on piping materials.
- In any commercial kitchen application involving three-compartment sinks and food waste disposers.
- For venting any residential bathroom group, including toilets, lavatories, and showers.
Correct answer: For floor drains and sinks in specific applications like laboratories where conventional venting is structurally impractical.
Combination waste and vent systems are specialized systems permitted only where structural conditions prevent the installation of a conventional vent system. They are typically used for fixtures like floor drains and sinks in locations such as laboratories or island sinks, where the oversized horizontal drain pipe also serves as the vent.
Question 2: A journeyman plumber is installing a horizontal run of 2-inch Schedule 40 PVC drainpipe. According to the International Plumbing Code (IPC), what is the MAXIMUM allowable spacing between hangers or supports for this pipe?
- Every 2 feet
- Every 4 feet (Correct answer)
- Every 5 feet
- Every 10 feet
Correct answer: Every 4 feet
The IPC Table 308.5 specifies the maximum horizontal support spacing for various piping materials to prevent sagging and maintain the required slope. For all sizes of PVC pipe, the maximum allowable spacing between supports is 4 feet.
Question 3: When performing a water test on a newly installed DWV (Drain, Waste, and Vent) system, what is the minimum required head of water that must be applied to the system and for what duration, according to the IPC?
- 5 feet of head for 10 minutes.
- The system must be filled to the point of overflow for 5 minutes.
- 10 feet of head for 15 minutes. (Correct answer)
- A head equal to a 2-story building (approx. 20 feet) for 30 minutes.
Correct answer: 10 feet of head for 15 minutes.
According to IPC Section 312.2, a water test on a DWV system requires it to be subjected to not less than a 10-foot head of water. This pressure must be held for a minimum of 15 minutes without any evidence of leakage.
Question 4: A plumber is installing a 4-inch horizontal building drain that makes a single 90-degree turn. Which of the following statements about cleanout requirements is correct according to most plumbing codes?
- A cleanout is only required if the total length of the drain exceeds 100 feet.
- A cleanout can be omitted if two 45-degree fittings are used to make the turn.
- A cleanout is not required if a fixture with a removable trap is located within 5 feet of the turn.
- A cleanout is required at each change of direction greater than 45 degrees. (Correct answer)
Correct answer: A cleanout is required at each change of direction greater than 45 degrees.
Plumbing codes, such as the IPC Section 708.1.4, mandate the installation of cleanouts to allow access for clearing blockages. For horizontal drainage pipes, a cleanout is explicitly required at each change of direction that is greater than 45 degrees.
Question 5: Which of the following is explicitly PROHIBITED by code for the discharge pipe of a water heater's Temperature and Pressure (T&P) relief valve?
- Installing any type of shutoff valve or tee fitting in the line. (Correct answer)
- Terminating the pipe 6 inches above a floor drain.
- Constructing the pipe from approved materials like copper or CPVC.
- Pitching the pipe downwards to allow for drainage by gravity.
Correct answer: Installing any type of shutoff valve or tee fitting in the line.
The discharge line from a T&P valve is a critical safety feature that must remain unobstructed at all times. Installing any valve, tee, or other potential obstruction is strictly prohibited by plumbing codes (IPC 504.6) as it could prevent the valve from relieving dangerous excess pressure or temperature.
Question 6: A plumber is setting a water closet in a residential bathroom. According to the International Plumbing Code (IPC), what is the MINIMUM required clearance from the centerline of the water closet to an adjacent side wall or vanity?
- 12 inches
- 15 inches (Correct answer)
- 18 inches
- 21 inches
Correct answer: 15 inches
IPC Section 405.3.1 specifies the minimum spacing for plumbing fixtures to ensure accessibility and ease of use. A water closet cannot be set closer than 15 inches from its center to any side wall, partition, or vanity.
